Power supplies in electronic devices such as computer systems typically output at least one direct current (DC) electric power signal, used to power the various electronic components comprising the electronic device. This electric power signal is distributed throughout most circuits, and used to power various circuit elements including amplifiers, digital logic, and discrete circuitry. But, it is not uncommon for each of these devices to require a different power supply voltage, making the task of producing and distributing power signals of proper voltages to each component difficult.
For example, many amplifier circuits require 15 volts potential or more in supplied power, and digital logic often requires only 5 volts. Many newer low-voltage digital logic devices operate on power supplied at even lower voltages, including 3.3 volts and 2.5 volts in some devices. Mixing devices requiring various voltage levels in a single electronic device not only requires ensuring input and output signals from the various components are at proper voltage levels, but also requires ensuring that power is supplied at all voltages needed by the various components.
One solution to the problem is to use a circuit known as a DC-DC converter, which includes a broad class of electronic circuits that convert DC power supplied at a certain potential or voltage to DC power at a different voltage. Use of multiple DC-DC converters in an electronic device provides the ability to support a variety of DC voltage requirements for various devices without requiring multiple power supplies.
Because DC-DC converters are usually relied upon to provide a specified DC output voltage that remains within the voltage requirements of electronic circuits, they are typically designed to provide a voltage that remains within a specified voltage range over an anticipated range of load conditions. For example, a rapid increase in current drawn often causes a temporary undesired reduction in output voltage of a DC-DC converter. This voltage drop must be accurately characterized, so that the DC-DC converter can be relied upon to maintain an adequate output voltage for a specified maximum increase in current drawn. Similarly, a rapid decrease in current drawn can result in a temporary undesired increase in output voltage, which must be similarly characterized to ensure that the voltage increase does not exceed the voltage range required by the electronic circuitry.
One solution to the problem of regulating the output voltage in changing current conditions is to utilize an adaptive voltage positioning DC-DC converter that has an intentionally varying output voltage for different current loads, such that the output voltage is at a relatively low potential under a high current load and at a relatively high potential under a no current load. A change in current load will then cause the output voltage to temporarily change in a direction that is compensated for by the variable output voltage, as is explained in greater detail herein. But, the design of such DC-DC converters does not anticipate that certain load devices may draw typical current loads that do not span a full range of maximum current draw to no current draw but rather typically draw current in a narrow range of currents the DC-DC converter can provide, making a linear adaptive voltage response less than optimal for those applications.
What is needed is a nonlinear adaptive voltage positioning method and apparatus for a DC-DC converter that enable improved voltage transient response under changing current conditions for a load with known current draw characteristics that do not span the entire range of current the DC-DC converter is capable of providing.